Human Schlafen 5 regulates reversible epithelial and mesenchymal transitions in breast cancer by suppression of ZEB1 transcription

Background Human Schlafen 5 (SLFN5) has been reported to inhibit or promote cell invasion in tumours depending on their origin. However, its role in breast cancer (BRCA) is undetermined. Methods Differential expression analyses using The Cancer Genome Atlas (TCGA) data, clinical samples and cell lines were performed. Lentiviral knockdown and overexpression experiments were performed to detect changes in cell morphology, molecular markers and invasion. Chromatin immunoprecipitation-sequencing (ChIP-Seq) and luciferase reporter assays were performed to detect the SLFN5-binding motif. Results TCGA, clinical samples and cell lines showed that SLFN5 expression was negatively correlated with BRCA metastasis. SLFN5 knockdown induced epithelial–mesenchymal transition (EMT) and enhanced invasion in BRCA cell lines. However, overexpression triggered mesenchymal–epithelial transition (MET). SLFN5 inhibited the expression of ZEB1 but not ZEB2, SNAI1, SNAI2, TWIST1 or TWIST2. Knockdown and overexpression of ZEB1 indicated that it was a mediator of the SLFN5-governed phenotype and invasion changes. Moreover, SLFN5 inhibited ZEB1 transcription by directly binding to the SLFN5-binding motif on the ZEB1 promoter, but a SLFN5 C-terminal deletion mutant did not. Conclusion SLFN5 regulates reversible epithelial and mesenchymal transitions, and inhibits BRCA metastasis by suppression of ZEB1 transcription, suggesting that SLFN5 could be a potential target for BRCA therapy.